100GBASE-ER4 QSFP28 Optical Module - 40km 1310nm QSFPTEK

In this review of the 100GBASE-ER4 QSFP28 optical module, the bottom line is clear: it is designed for network engineers and data center operators who need reliable long-distance 100G links compatible with Cisco coding. The module offers up to 40km reach over standard single mode fiber with duplex LC connectors and supports 100GBASE-ER4 and CAUI-4 standards, making it a straightforward replacement or spares option for environments that require interoperable, hot-pluggable optics with built-in diagnostics.

Key Features

• Cisco compatible coding: Works as a drop-in compatible transceiver for devices expecting Cisco QSFP-100G-ER4L-S coding, simplifying replacements and inventory.
• 40km single mode reach: Delivers long distance transmission over SMF at 1310nm, suitable for campus or metropolitan links without regeneration.
• Four full-duplex channels: Uses 4 independent channels to provide a native 100G link with CAUI-4 electrical interface compatibility.
• Low power and hot pluggable: Consumes about 4.5W and supports hot swap, reducing power cost and easing maintenance in live equipment racks.
• DDM diagnostics: Built-in digital diagnostic monitoring helps verify signal and module health for faster troubleshooting.
• Standards and safety: Complies with IEEE 802.3ba/3bm and is Class 1 FDA laser safety and RoHS compliant for regulated deployments.

Who It's For

This module is best for enterprise core and distribution layers, high-performance computing networks, and large data center interconnects that require a cost-effective, standards-based 100G optical solution. Operators replacing failed Cisco-branded modules or stocking interoperable spares will value the Cisco-compatible coding and hot-pluggable form factor.

It is less appropriate for short-reach optics needs or links using multimode fiber, and buyers requiring vendor support bundles should confirm their support policies since this is a compatible third-party module rather than an original manufacturer spare.

Pros & Cons

Pros

• Up to 40km single mode reach at 1310nm, enabling long distance backbone and metro links.
• Low power consumption around 4.5W and hot-pluggable design simplify operations and reduce thermal load.
• Built-in DDM offers real-time diagnostic data to speed troubleshooting and maintenance.
• Compatible coding for Cisco QSFP-100G-ER4L-S reduces compatibility headaches when replacing modules.

Cons

• Not intended for multimode fiber or short-reach use; buyers must confirm fiber type and connector compatibility.
• Vendor support differs from original manufacturer parts, so enterprise buyers should plan replacement and maintenance accordingly.

Specifications

Form factor	QSFP28 (100GBASE-ER4)
Wavelength	1310nm
Maximum reach	Up to 40km over single mode fiber
Connectors	Duplex LC
Power consumption	Approximately 4.5W
Standards	IEEE 802.3ba 100GBASE-ER4, IEEE 802.3bm CAUI-4
Operating temperature	0C to 70C (32 to 158F)

Our Verdict

The 100GBASE-ER4 QSFP28 module is a practical, standards-compliant option for teams that need reliable 100G long-reach links with Cisco-compatible coding. It balances low power, built-in diagnostics, and a 40km single mode reach to offer good value as a replacement or spare in data centers and metro networks, provided buyers accept third-party support arrangements.

Frequently Asked Questions

Is this module compatible with Cisco switches?
Yes, it is coded to be compatible with Cisco QSFP-100G-ER4L-S coding to work as a drop-in replacement on many Cisco systems, but verify software and hardware compatibility first.

What fiber type and connector are required?
This module requires single mode fiber (SMF) with duplex LC connectors for links up to 40km at 1310nm.

Does it support diagnostic monitoring?
Yes, it includes DDM (digital diagnostic monitoring) for real-time module and signal health information.